Exponential and local Lamb waves in the nonisothermal atmosphere as an obstacle to the acoustic-gravity disturbance propagation up to the ionosphere

•Lamb waves in a nonisothermal atmosphere studied analytically and numerically.•An exponential Lamb wave exists near the layer with an extremum of sound speed.•A local wave exists if the horizontal phase velocity is equal to the sound speed.•The local waves are the reason for a filtration of atmospheric disturbances.•Such filtration is an obstacle to the acoustic-gravity wave upward propagation.

In this study generalized Lamb waves in a nonisothermal atmosphere have been examined theoretically. Our results suggest that the pressure component of the Lamb wave decreases exponentially upwards near the layer with an extremum of sound speed. We find that local wave disturbances of the wave pressure component are formed in the resonance layer at which the horizontal phase velocity is equal to the sound speed. These resonance layers are the reason for a filtration of atmospheric disturbances. Such filtration is an obstacle to the acoustic-gravity wave propagation up to the ionosphere.